Means for purifying the exhaust discharge of internal combustion engines

ABSTRACT

A device for purifying the exhaust discharge of an internal combustion engine including a housing in which is a heat retaining member formed from unglazed, porous ceramic material and arranged such that the exhaust gases pass both over its outer surface in a space between the heat retaining member and the inner wall of the housing and through the porous ceramic member, the heat retaining member having an end portion of tapering cross-section with its narrow end which is closed directed towards the incoming exhaust stream, and means being provided for admitting air to the housing before the exhaust stream comes into contact with the heat retaining member.

United States Patent [191 Morrall Oct. 7, 1975 [76] Inventor: James W. Morrall, 16 Ashendene Grove, Hanford, Stoke-on-Trent, England 22 Filed: Jan. 15, 1973 21 Appl. No.: 323,559

[52] U.S. Cl. 23/277 C; 60/303 [51] Int. Cl. FOlN 3/10; F236 7/06 [58] Field of Search 23/277 C, 288 F, 288 PC; 60/303 [56] References Cited UNITED STATES PATENTS 2,038,567 4/1936 lttner 60/303 X 2,203,554 6/1940 Uhri, Jr. et a1. 23/277 C 2,649,685 8/1953 Cohen 23/277 C 2,831,548 4/1958 Barke1ew.... 60/303 X 2,956,865 10/1960 Williams 60/303 X 3,065,595 11/1962 Gary 60/303 X 3,170,280 2/1965 Rees 60/303 3,435,613 4/1969 Eannarino et a1 23/277 C 3,460,916 8/1969 Aronsohn 23/277 C X 3,683,625 8/1972 McCrink 60/303 X 3,706,533 12/1972 Brewer 23/288 F X Primary Examiner.loseph Scovronek Assistant Examiner-Arnold Turk Attorney, Agent. or FirmAlan H. Levine [5 7] ABSTRACT A device for purifying the exhaust discharge of an internal combustion engine including a housing in which is a heat retaining member formed from unglazed, porous ceramic material and arranged such that the exhaust gases pass both over its outer surface in a space between the heat retaining member and the inner wall of the housing and through the porous ceramic member, the heat retaining member having an end portion of tapering cross-section with its narrow end which is closed directed towards the incoming exhaust stream, and means being provided for admitting air to the housing before the exhaust stream comes into contact with the heat retaining member.

8 Claims, 9 Drawing Figures U.S. Patnt Oct. 7,1975 Sheet 1 Of3 3,910,762

US. Patent Oct. 7,1975 Sheet 2 of3 3,910,762

US. Patent Oct. 7,1975 Sheet 3 01 3 3,910,762

mm R ww r| aw m m Nm 3 T N R R R LE f 1 a m i. L: /V m Q w 33 1 w a 4 4 .7 M R E r EILI. an R Tm w mq MEANS FOR PURIFYING THE EXHAUST DISCHARGE OF INTERNAL COMBUSTION ENGINES The invention relates to means for purifying the exhaust discharge of internal combustion engines.

The invention provides a device for purifying the exhaust discharge of an internal combustion engine, the device including a housing having located therein a heat-retaining member formed from unglazed porous ceramic material and arranged such that the exhaust gases pass over its outer surface in a space between the latter and the inner wall of the housing, the heatretaining member having an end portion of tapering cross-section with its narrow end directed towards the incoming exhaust stream, and there being means for admitting air to the housing before the exhaust stream comes into contact with the heat-retaining member.

Preferably the heat-retaining member has a helical channel in its outer surface serving to guide the gases round the surface and thereby increase the length of their path of contact with the member and the period of contact.

The device may be located in any position in the engine exhaust system or in a position close to but slightly spaced from the tail pipe. Preferably however the device is located as close as possible to the engine in order that the heat-retaining member may be maintained at a high temperature.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. I is a side elevation of one form of device incorporated in the tailpiece of a motor vehicle exhaust systern;

FIG. 2 is a vertical crosssection through the device shown in FIG. 1;

FIG. 3 is a view in the direction of arrow III in FIG.

FIG. 4 is a section on the line IV IV in FIG. 5;

FIG. 5 is a side elevation of a modified device incorporating two heat retaining members in series;

FIG. 6 is a section on the line VI VI in FIG. 5;

FIG. 7 is a side elevation of a further form of device;

FIG. 8 is a vertical cross-section through the device shown in FIG. 7; and

FIG. 9 is a section on the line IX IX in FIG. 8.

Referring to FIGS. 1 to 3 the device comprises a unit adapted to be fitted to the tail pipe 10 of the vehicle exhaust system, the unit having a metal housing 11 provided with brackets I2 enabling it to be attached to a suitable part of the vehicle. Within the housing 11 a tapered hollow heat retaining member 13 formed from unglazed porous ceramic material is supported in front and rear by support brackets 14 and 15 respectively, with the small diameter end of the member being closed and directed towards the tail pipe 10. A spiral groove or channel 16 is formed in the member 13 and serves to form a tortuous path around which exhaust gases travel in contact with the surface of the member in their travel through the device. An air inlet opening 17 is provided adjacent the forward end of the housing 11. This opening allows entry of clean air into the housing for mixture with the exhaust stream before the latter impinges on the heat retaining member 13. The inlet 17 is closed by a perforated gauze 18 (FIG. 3) and a baffle plate 19 (FIG. 2) serves to prevent escape of exhaust gases to atmosphere. This will not occur during normal running of the engine but could take place under idling conditions. The exhaust products are finally discharged to the atmosphere through an outlet pipe 20.

The arrangement of FIGS: 1 to 3 may be readily fitted in position on the rear of the existing exhaust system. However since it is a considerable distance away from the engine the heat retaining member does not receive and absorb a great amount of heat and this form of device also tends to produce a certain amount of back pressure. FIGS. 4 to 6 illustrate an alternative arrangement which may be fitted to the exhaust system in a position nearer to the engine. The unit includes a casing 21 within which two heat retaining members 22, 23 are mounted in suitable supports 24. Internal baffles 25 and 26 are provided and direct the exhaust stream over the two heat retaining members in turn. The heat retaining members are closed at their narrow ends and are provided with spiral channels 27 similar to those described with reference to FIGS. 1 to 3 and these channels together with the baffles 25 and 26 form a path of considerable length around and along which the exhaust gases travel. The gases are therefore maintained in contact with the heat retaining members for a considerable period of time. A venturi device 28 is provided adjacent the inlet to the unit and serves to permit clean air to be drawn into the unit while preventing escape of exhaust gases. Since this unit is located closer to the engine a considerable amount of heat will be transmitted to and absorbed by the two heat retaining members and this increases the efficiency of purification of the exhaust gases compared with the arrangement of FIGS. 1 to 3.

FIGS. 7 to 9 illustrate a further modification which may be fitted at the manifold end of the exhaust pipe or at the rear ofa unit such as that described with reference to FIGS. 4 to 6. The arrangement shown in FIGS. 7 to 9 includes an outer cylindrical metal casing 30 with which inlet and outlet pipes 31 and 32 communicate. Within the casing 30 a tubular ceramic or refractory sleeve 33 provided with a series of perforations 34 is supported in end pieces 35 and 36. A heat retaining member 37 closed at its narrow end and having a spiral channel 38 formed in its outer surface is supported by suitable supports 39. A venturi device 40 is provided at the inlet end of the casing to permit entry of clean air while preventing escape of exhaust gases.

The precise manner in which the devices described above function to purify exhaust gases is not fully understood but is believed to be as follows. The heat retaining member receives heat from the hot exhaust gases and retains this heat thereby raising the temperature within the device well above that which would be attained by mere passage of the gases through the housing. The provision of the spiral channel in the heat retaining member forms an extended path along which the exhaust gases pass in contact with the high temperature outer surface of the heat retaining member. In the case of the arrangement described with reference to FIGS. 4 to 6 the path is considerably increased due to the provision of two heat retaining members in series.

The introduction of clean air then creates the situation that solid particles of carbon and other impurities together with incompletely burnt gases are subjected to a sufficient temperature for a sufficient period of time in an atmosphere containing sufficient oxygen to promote further combustion. Carbon, hydrocarbons, lead acids and hydrogen are thereby burnt and carbon monoxide oxidised to carbon dioxide, this carbon dioxide being discharged to atmosphere and the residue of the burnt constituents being deposited on the heat retaining member. The efficiency of the process has been found to increase with increase in temperature of the heat retaining member so that those arrangements positioned closest to the engine have the greatest efficiency.

A further advantage of devices according to the invention is that they are self cleaning. At vehicle speeds above about 45 miles per hour the extent of pollution of the exhaust gas stream is much less than at lower speeds. At these higher speeds the residue deposited on the heat retaining member will be dried and crystallized, the crystals will be removed by the outgoing exhaust stream, and in this way the heat retaining member is restored to its original condition. If fitted to vehicles designed only for very low speeds the devices could of course be constructed in a manner enabling removal of the heat retaining members periodically for cleaning treatment.

It should be noted that the inner ceramic sleeve 33 of the arrangement shown in FIGS. 7 to 9 serves to concentrate more heat on to the heat retaining member thereby increasing its efficiency.

Various modifications may be made without departing from the scope of the invention as defined in the appendent claims. For example, the heat retaining member or members could be arranged such that the exhaust gas stream passes through each member as well as over it. The relative dimensions of the heat retaining member and housing may be altered as desired and any convenient number of heat retaining members may be arranged in series or in parallel to increase the length of the contact path and the period of contact. Alternatively a number of devices such as those illustrated could be used in combination, and the invention is of course applicable to engines other than motor vehicle engines.

I claim:

its outer surface in a space between the latter and the inner wall of the housing and through the porous material to the hollow interior, the heat-retaining member having an end portion of tapering cross-section with its narrow end closed and directed towards the incoming exhaust stream and a helical channel in the outer surface of the member serving to guide the gases around the surface and thereby increase the length of their path of contact with the member, the heat generated within the device being derived solely from the exhaust gases, and means for admitting air into the exhaust stream upstream of the heat-retaining member.

2. A device according to claim 1 wherein said means for admitting air includes means to prevent escape of exhaust products through the air inlet.

3. A device according to claim 1 including a plurality of heatretaining members arranged in series.

4. A device according to claim 3 wherein said heat retaining members are arranged side-by-side and baffle means is provided to direct the exhaust stream over the members in turn.

5. A device according to claim 1 wherein the heatretaining member is surrounded by a sleeve member of heat-retaining material spaced from both the heatretaining member and the housing.

6. A device according to claim 5 wherein the sleeve is made from ceramic material.

7. A device according to claim 1 including means for connecting said inlet and said outlet to an internal combustion engine exhaust system.

8. A device according to claim 7 including means for connecting said inlet directly to an internal combustion engine exhaust manifold. 

1. A DEVICE FOR PURIFYING THE EXHAUST DISCHARGE OF AN INTERNAL COMBUSTION ENGINE, THE DEVICE INCLUDING A HOUSING HAVING AN INLET AND AN OUTLET, A HOLLOW HEAT-RETAINING MEMBER LOCATED WITHIN THE HOUSING AND OCCUPYING A SUBSTANTIAL PART OF THE HOUSING, SAID MEMBER BEING FORMED FROM UNGLAZED POROUS CERAMIC MATERIAL AND ARRANGED SUCH THAT THE EXHAUST GASES MAY PASS OVER ITS OUTER SURFACE IN A SPACE BETWEEN THE LATTER AND THE INNER WALL OF THE HOUSING AND THROUGH THE POROUS MATERIAL TO THE HOLLOW INTERIOR, THE HEAT-RETAINING MEMBER HAVING AN END PORTION OF TAPERING CROSS-SECTION WITH ITS NARROW END CLOSED AND DIRECTED TOWARDS THE INCOMING EXHAUST STREAM AND A HELICAL CHANNEL IN THE OUTER SURFACE OF THE MEMBER SERVING TO GUIDE THE GASES AROUND THE SURFACE AND THEREBY INCREASE THE LENGTH OF THEIR PATH OF CONTACT WITH THE MEMBER, THE HEAT GENERATED WITHIN THE DEVICE BEING DERIVED SOLELY FROM THE EXHAUST GASES, AND MEANS FOR ADMITTING AIR INTO THE EXHAUST STREAM UPSTREAM OF THE HEAT-RETAINING MEMBER.
 2. A device according to claim 1 wherein said means for admitting air includes means to prevent escape of exhaust products through the air inlet.
 3. A device according to claim 1 including a plurality of heat-retaining members arranged in series.
 4. A device according to claim 3 wherein said heat retaining members are arranged side-by-side and baffle means is provided to direct the exhaust stream over the members in turn.
 5. A device according to claim 1 wherein the heat-retaining member is surrounded by a sleeve member of heat-retaining material spaced from both the heat-retaining member and the housing.
 6. A device according to claim 5 wherein the sleeve is made from ceramic material.
 7. A device according to claim 1 including means for connecting said inlet and said outlet to an internal combustion engine exhaust system.
 8. A device according to claim 7 including means for connecting said inlet directly to an internal combustion engine exhaust manifold. 